Saudi-exile Osama bin-Laden is seen addressing a news conference in Afghanistan, where he and his organization are based, in this May 26, 1998 file photo. The U.S. on Thursday started to gear up for what it called the first war of the 21st century, naming bin Laden as a suspect in twin terror attacks that stunned New York and Washington. The leader of Afghanistan's ruling Taliban movement on Friday defended bin Laden against accusations he mastermind the devastating attacks. REUTERS/Str/File photo

Photo: STR/PAKISTAN

Saudi-exile Osama bin-Laden is seen addressing a news conference in...

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In this image from television Ali Mohamed, 48, a former Army sergeant is seen in an undated U.S. military video teaching soldiers in the American special forces about Muslim culture. Ali Mohamed pleaded guilty Friday, Oct. 20, 2000, to helping plot the deadly U.S. embassy bombings in Africa, admitting he joined terrorist mastermind Osama bin Laden and others in a holy war to kill Americans anywhere they could be found. (AP Photo/CNN)

In this image from television Ali Mohamed, 48, a former Army...

Bin Laden's man in Silicon Valley / "Mohamed the American' orchestrated terrorist acts while living a quiet suburban life in Santa Clara

He was the California connection to Osama bin Laden's fearsome terrorist organization -- an architect of horrific acts of violence against his adopted country, even as he lived a quiet suburban lifestyle in Silicon Valley.

For much of a decade he commuted from the West Coast to the terrorist camps of Afghanistan and Sudan, where he trained bin Laden's men in guerrilla military tactics, surveillance and explosives.

The unsuspecting Americans who met him in his duplex in Santa Clara knew him as Ali A. Mohamed, a cordial, under-employed Egyptian immigrant with an Army background, a U.S.-born wife and frequent business abroad.

But to his fellow terrorists, he was Abu Mohamed ali Amriki -- "Mohamed the American" -- a hard-driving military taskmaster who trained bin Laden's own personal security cadre and was a top aide and confidant of the shadowy terrorist kingpin himself.

Until his 1998 arrest for plotting the terror bombing of two U.S. embassies in East Africa, Mohamed "was the California connection, period," for bin Laden,

said lawyer Sam A. Schmidt, who defended another accused terrorist in the embassy bombing trial this year.

Now in prison and presumed to be a government informant, Mohamed could be a key connection for U.S. investigators probing bin Laden's links to the suicide hijackers who flew jetliners into the World Trade Center and Pentagon last week, some experts say.

In remarks to a judge last year when he pleaded guilty to terrorism charges,

Mohamed admitted a long list of such crimes: training guerrillas who attacked U.S. soldiers in Somalia in 1993; arranging a summit conference of anti-U.S. terrorist organizations in Sudan in 1994; plotting the suicide bombings of American embassies in Kenya and Tanzania, which killed more than 200 people and injured thousands.

Other suspected activities during his California days include raising money for the Egyptian Islamic Jihad, implicated in the 1981 assassination of Egyptian President Anwar Sadat, and smuggling sleeper agents for bin Laden into the United States from Canada.

For the U.S. government, Mohamed is important today because he has extraordinary insights into the inner workings of bin Laden's al Qaeda organization, says Yonah Alexander, director of the Potomac Institute's Center for Terrorism Studies in Washington, D.C., who has researched Mohamed's life. He may even have had personal contacts with some of the hijackers responsible for last week's attacks.

"In his previous life, perhaps he trained some of these people," Alexander said. "Clearly (the government) has interrogated him, and we assume they are doing it now, because he is a very important source."

Mohamed's story also is important because it shows how easily even a top- level terrorist can operate unmolested and undetected from the very heart of the United States.

Terrorist groups have "woven themselves into the fabric of America," said Harvey Kushner, an international security expert and professor at Long Island University. "That is why this is going to be a long, protracted war (against terrorism). The enemy is not outside, it's within us."

TRIAL RECORDS REVEAL

MOHAMED'S SECRET LIFE

The details of Mohamed's two lives were obtained from court records generated during two major terrorism trials, from defense lawyers and security experts who have investigated his background and from people who knew him in California.

By these accounts, Mohamed, 49, is a well-educated Egyptian national, fluent in English, who graduated from both the University of Alexandria and a Cairo military academy. In about 1971, he joined the Egyptian army, rising to the rank of major.

As he told a federal judge in New York last year, his links to Middle Eastern terrorist groups go back 20 years: In 1981, he joined the Egyptian Islamic Jihad, a group of radical Muslim fundamentalists opposed to the Egyptian government's ties to the United States and Israel that included members of the Egyptian military.

That same year Mohamed first visited the United States, graduating from a special program for foreign officers at the U.S. Army Special Forces school at Fort Bragg, N.C., according to a report by Steven Emerson, an author and terrorism expert.

Mohamed left the Egyptian army about three years after Sadat's death, then worked for a time as security adviser for EgyptAir, the national airline, said attorney David Ruhnke, who researched Mohamed's history for the embassy bombing trial.

Shortly after that, the terrorist operative returned to the United States and established himself in the Bay Area after romancing an American divorcee whom he met on a transatlantic flight in 1985.

Mohamed was traveling from Egypt to New York, he said, while the divorcee, a medical technician from Santa Clara, was returning to the West Coast after a vacation in Greece, according to two longtime acquaintances who asked not to be named because of safety concerns.

Within a few days of arriving in the United States, Mohamed phoned the divorcee and then turned up in the Bay Area, according to the acquaintances. After a six-week courtship, they were married in Reno.

Mohamed's wife seemed genuinely devoted to her husband, but the acquaintances suspected that, for him, it may have been "a marriage of convenience," as one put it -- a way to obtain a "green card" and an American home.

Mohammed moved into his new wife's Santa Clara duplex. People who met him there said he was cordial, well-spoken and physically fit; he described himself as a former Egyptian army officer who hoped to do intelligence work for the United States.

But that didn't pan out, and after a year of unemployment, he enlisted in the U.S. Army.

While his wife remained in California, Mohamed became a sergeant and was again stationed at Fort Bragg's Special Warfare Center, where he trained officers in Middle Eastern culture and geography. He also became a U.S. citizen, his associates said.

But even while an American soldier, court records show, Mohamed worked on behalf of militant Islamic groups.

In the late 1980s, he turned up in a Brooklyn, N.Y., refugee center for people displaced by the Soviet invasion of Afghanistan, according to evidence in the 1995 trial of El Sayyid Nosair, an Egyptian terrorist convicted of plotting to bomb the U.N. headquarters in New York.

In Brooklyn, Mohamed gave combat training to Muslim recruits bound for Afghanistan to fight the Soviet invasion, said defense lawyer Roger Stavis. Nosair was among the guerrilla fighters Mohamed trained, he said.

Although the United States was then providing training and money to the anti-Soviet rebels, the government said Mohamed's activities were unauthorized.

SPENDING MORE TIME

AWAY FROM HOME

Mohamed was discharged from the army in 1989. He returned to Santa Clara, where he served for a time in the Army Reserve and tried but failed to get a job as an FBI interpreter, according to lawyers familiar with his background.

He worked as a security guard at the old Sylvania plant in Mountain View, acquaintances said, and ran a computer consulting firm out of his home.

Mohamed often complained that he couldn't find a good job and, after a time,

according to his acquaintances, he began spending months abroad, saying he had found work in Egypt. For long periods he was out of touch.

His wife "would say he's in the desert, and he can't call me," one acquaintance recalled.

For some of his overseas jobs, Mohamed seemed not to be paid in money. Instead, "he'd bring back 24-karat gold bracelets," the acquaintance recalled.

And at one point in the early 1990s, Mohamed's wife told one of the acquaintances that her husband was in Afghanistan, training people for a man named bin Laden. At the time the name was virtually unknown in this country, and it seemed to mean nothing to the wife.

"Maybe I am dumb, but I did not know who this guy was, bin Laden," this person said. "I just didn't know."

GETTING TOGETHER

WITH BIN LADEN

Mohamed's 1980s work with the Egyptian Islamic Jihad eventually drew him to bid Laden, the multimillionaire son of a Saudi construction magnate.

Bin Laden, who had helped finance and train the Islamic guerrillas who finally expelled the Soviet invaders from Afghanistan in 1989, became increasingly anti-American after the United States defeated Iraq in the 1991 Persian Gulf War, and he began advocating a holy war to drive America from the Middle East.

He founded al Qaeda ("the base"), the terrorist organization implicated in a long list of deadly anti-American attacks.

"I was involved in the Islamic Jihad organization, and the Islamic Jihad organization had a very close link to al Qaeda, the organization for bin Laden, " Mohamed told the New York judge. "And the objective of all this, just to attack any Western target in the Middle East, to force the government of the Western countries just to pull out from the Middle East."

L'Houssaine Kherchtou, a onetime bin Laden guerrilla who turned U.S. government witness in the embassy bombing trial, said he had met Mohamed -- he called him "Amriki" -- in 1991 at a camp near Peshawar, Pakistan.

Mohamed, he said, was a high-ranking member of al Qaeda, a "very, very strict and not gentle" taskmaster who trained cadre members in how to reconnoiter targets for terror bombings.

Mohamed told the judge that in 1992 he had been in Afghanistan, providing "military and basic explosives training" to bin Laden's terrorists. The curriculum also included intelligence trade craft: "I taught my trainees how to create cell structures that could be used for operations," he said.

There were other tasks as well. In 1991, Mohamed said, he helped relocate bin Laden from Afghanistan to the African nation of Sudan, where the multimillionaire set up another network of paramilitary camps.

In about 1992, Mohamed said, he helped set up an al Qaeda cell in Nairobi, Kenya, along with a car business to earn money and a refugee-assistance charity that provided fake IDs for the terrorist gang.

In 1993, Mohamed said, bin Laden told him to scout prospective bombing targets in Nairobi, as bin Laden wanted a strike to retaliate for that year's U.S. intervention in Somalia.

Mohamed said he had scouted the French Embassy, the U.S. AID office and the U.S. Embassy. He took photos and maps to Khartoum for a meeting with the terrorist boss.

"Bin Laden looked at the picture of the American Embassy and pointed to where a truck could go as a suicide bomber," Mohamed told the court.

The Santa Clara resident also said he had arranged security for a conference in which bin Laden's al Qaeda met with Imad Mughniyeh, security chief for Hezbollah, the Iran-sponsored organization reputedly responsible for attacks that included the 1983 bombing of a U.S. Marine barracks in Lebanon that killed 241.

In 1994, while he was at the al Qaeda cell in Nairobi, Mohamed came under FBI suspicion in connection with a probe of Sheikh Omar Abdel-Rahman, a blind Islamic cleric arrested and ultimately convicted for masterminding the 1993 bombing of the World Trade Center, which killed six and injured 1,000.

At the FBI's request, Mohamed said, he flew to the United States to be interrogated. Mohamed lied to the FBI, claiming no links to terror, admitting only that he had trained Islamic guerrillas to fight the Russians in Afghanistan.

After that, Mohamed said, al Qaeda told him not to return to Nairobi. From his home in Santa Clara, he began tracking the Rahman case for bin Laden, relaying what he could learn about the progress of the FBI probe. He also made telephone calls from his home in California to bin Laden associates in Nairobi,

according to court testimony.

While back in California, Mohamed said, he did other tasks for bin Laden. Twice, he said, he aided the terrorist Ayman al-Zawahiri, a co-founder of the Egyptian Islamic Jihad, by then an aide to bin Laden and later a suspect in the embassy bombings, when he visited America to raise money.

Alexander, the Potomac Institute's terrorism expert, said intelligence sources believed Mohamed also had helped smuggle bin Laden agents into the United States via Canada.

Around 1997, Mohamed's acquaintances said, he and his wife moved to Sacramento, where he worked for a video distribution company.

On Aug. 7, 1998, terrorist bombs exploded at U.S. embassies in Nairobi and in Dar-Es-Salaam, Tanzania. Mohamed was again an FBI suspect. Court records show that 10 agents searched his Sacramento apartment, downloading the entire contents of Mohamed's two computers and photographing documents in English and Arabic found inside.

Among the documents were terrorist training manuals, describing surveillance and assassination techniques, and instructions on how to plant explosives to blow up buildings.

When he pleaded guilty, Mohamed said that after the embassy bombings, he had planned to leave the United States and return to Afghanistan to meet with bin Laden. Before he could get away, he was subpoenaed to testify before a U.S.

grand jury in New York.

"I testified, told some lies and was arrested," he said.

ADMITS PLAN TO KILL

SOLDIERS, DIPLOMATS

Mohamed was indicted along with bin Laden and 22 other alleged terrorists. Only six were brought to trial. In October 2000, Mohamed, who was facing the death penalty if convicted, pleaded guilty to five conspiracy charges, including plotting to kill U.S. soldiers in Somalia and Saudi Arabia, plotting to murder U.S. ambassadors and other embassy officials and plotting to kill "United States civilians anywhere in the world," as another prosecutor, Patrick Fitzgerald, summarized the charges.

But he has never been sentenced, and defense lawyers and security experts believe he had begun giving evidence about bin Laden to the government in hopes of winning his release from prison.

Acquaintances said Mohamed's wife, who declined to talk to The Chronicle, had expressed surprise after his arrest, but she remained loyal, corresponding with him and visiting him in prison.

The acquaintances said they were shocked and troubled at how easily the terrorist they knew as Ali Mohamed had duped them.

"It boggles the mind that anyone who lived this close here could possibly have anything to do with something this horrible," said one. "It makes you wonder about anyone else we were so taken in by."

Said the other: "I wonder sometimes, when he saw how we lived, if he wasn't sorry. Or can they just live two lives?"

A TERRORIST'S DUAL LIFE

Ali Mohamed served as a key aide to terrorist leader Osama bin Laden, while leading a double life as a Northern California suburbanite. .